LONDON — The British Foreign Office on Wednesday defended spending almost $16 million to buy an apartment for a diplomat in New York as “the best possible deal and value for money” and a way to promote Britain’s business interests in the city.

The British government paid 12 million pounds, or about $15.8 million, for the property, a full-floor penthouse on the 38th floor of 50 United Nations Plaza, a 43-story condominium building that is a stone’s throw from the United Nations headquarters on the East Side of Manhattan.

It will be home to Antony Phillipson, the British consul general in New York. Mr. Phillipson is also Britain’s trade commissioner for North America, responsible for strengthening the bilateral trade relationship between Britain and the United States, among other duties.

“The government could afford a £12 million grace-and-favor penthouse in New York, but couldn’t spend money to rehouse Grenfell survivors,” Umaar Kazmi, a law student at the University of Nottingham, said on Twitter on Wednesday, referring to the 2017 fire at a high-rise building in London that killed more than 70 people.

“As ever, the government shows that these things are not a matter of cost, they’re a matter of political priorities,” he added.

Nearly a decade of government austerity has had profound effect on British society, slashing budgets for policing, housing and welfare.

A United Nations expert said late last year that efforts by the Conservative-led government to cut state spending were “entrenching high levels of poverty and inflicting unnecessary misery in one of the richest countries in the world.”

Christopher Phillips, a professor of international relations at Queen Mary University of London, called the purchase “yet another example of the ridiculousness of Brexit.”

“The U.K. has had to sell off many of its grander foreign properties to balance the books during austerity; and now splashes out on this penthouse to win previously unnecessary trade deals,” he wrote on Twitter on Wednesday.

A spokesman for the Foreign Office said it was in the process of selling Mr. Phillipson’s current residence, which is near the British Consulate on Second Avenue.

“We have secured the best possible deal and value for money on a property that will help promote the U.K. in the commercial capital of our largest export market and trading partner,” the spokesman said in an email. He confirmed that the sale had closed on March 15.

“As well as being the consul general’s residence, it will also be used to support his work to help British businesses” as trade commissioner for North America, he added.

Zeckendorf Development and Global Holdings, the developers of 50 United Nations Plaza, confirmed the sale in an email on Wednesday. The building — which also has a swimming pool, a garage, and a fitness center — was completed in 2014. It is on First Avenue between East 46th and East 47th Streets and was designed by the London architects Foster & Partners.

Mr. Phillipson’s 5,893-square-foot penthouse has seven bedrooms, including two for household staff; six bathrooms; a powder room; three walk-in closets; and a library, according to the floor plan.

In a review of 50 United Nations Plaza on the website CityRealty, Carter B. Horsley, a former real estate writer for The New York Times, described it as “a glittering scepter for modern pharaohs who demand spectacular sunrises.” With the sale to the British government, more than 80 percent of the building has now been sold, Zeckendorf Development said.